Automated assembly equipment, including robotic assembly equipment, commonly picks and places assembly components using some form of sensing mechanism to determine the presence of the assembly component at an end effector. When picking and placing the assembly component using a vacuum nozzle, typically a conventional vacuum sensor detects a change in air pressure at the nozzle that indicates the presence of the assembly component.
Regrettably, when the assembly component shape and dimensions are substantially different than the shape and dimensions of the nozzle (e.g. an airwound coil or a spring), the change in air pressure in many instances is not sufficient to reliably indicate the presence of the assembly component. This condition oftentimes is a significant cause of assembly and manufacturing failures. If the assembly component is not reliably detected and assembled during factory production, the quality of the manufactured product may be severely affected as perceived by the consumer.
Alternately, a proximity sensor, such as an infrared sensor, may be used to detect the presence of the assembly component. Because conventional proximity sensors tend to be relatively bulky for assembly of small components with tight assembly clearances, they are usually located at a station away from the automated assembly (e.g., robotic assembly). Unfortunately, these logistics demand that the assembly component be captured and then carried to the sensing station to determine the presence of the assembly component, adding significant time to the assembly process. Moreover, the sensing due to these conventional proximity sensors (e.g., infrared sensor), may also show high failure rates when the assembly component (e.g., a spring or an airwound coil), is small relative to the dimensions of the vacuum nozzle end effector. In many instances, the assembly component may be indistinguishable from the vacuum nozzle using these conventional proximity sensors.